Copper potential of KSK COW - Kalimantan Gold Corporation Limited

Copper potential of the Kalimantan Surya Kencana 

Contract of Work, Central Kalimantan, Indonesia 

Peter J. Pollard 

Pollard Geological Services Pty. Ltd. 

7 Jillinda Place, The Gap 

Queensland 4061, Australia 

peter@peterpollard.com 

January 2008

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Executive Summary 

The Kalimantan Surya Kencana Contract of Work in Central Kalimantan contains several 

porphyry copper-gold systems where recent exploration by Oxiana Limited in joint venture 

with Kalimantan Gold Corporation Limited included geological mapping, reprocessing of 

geophysical data and drilling 16 diamond drill holes. Many holes contained no significant 

copper mineralization and thereby downgraded parts of several prospects. Oxiana Limited 

withdrew from the joint venture in late 2007. 

Of the sixteen new holes, five were drilled in the Main Zone at Beruang Kanan. All 

encountered low-grade copper mineralization, with the best intersections being in KBK0021 

with 44m @ 0.58% Cu from 16.6m and 41.7m @ 0.46% Cu from 147m. The drilling did not 

test the deeper part of the main target previously proposed by Leach (2001) in the vicinity of 

BK09 and the mineralization is therefore open in this area. Similarly, two holes drilled in the 

South Zone at Beruang Kanan have not tested the main part of the coincident IP chargeability 

and copper in soil anomalies defined by previous work by Geiger et al. (2005). 

One hole drilled in Central Baroi targeted a conceptual geophysical and geochemical target 

but failed to intersect significant mineralization. Another hole was drilled in a base metal vein 

zone at Far East Baroi and confirmed earlier interpretations that there is no shallow porphyrystyle 

mineralization in this area. Two further targets in Central Baroi which were supported 

by the reprocessed IP data were not drilled. These remain targets for future exploration. 

Three holes were drilled at the Mansur prospect, two in the area of the main copper in soil 

anomaly and one targeting an IP anomaly further south. The holes returned no significant 

mineralization and indicate that it is highly unlikely an economic porphyry copper system is 

present at Mansur. 

Oxiana Limited drilled one hole at the Beruang Tengah prospect targeting high copper in rock 

chips as well as mapped phyllic alteration and milled breccia. The hole contained no 

significant copper mineralization and it was concluded that the prospect had no room to host a 

near-surface economic porphyry copper deposit. The prospect has been delineated by rock 

chip sampling of creek outcrops, but veining and surface limonite development extend 

beyond this area, particularly to the south and west. Although the recent drilling downgraded 

the current prospect area, there appears to be scope for further work at Beruang Tengah 

possibly involving an extended soil geochemical survey with IP and ground magnetics to help 

delineate further targets. 

No new drilling was carried out at Tumbang Huoi where the presence of copper in soil 

anomalies and widespread potassic alteration (biotite ± magnetite) in earlier drill holes 

suggest that this prospect may have some potential. Further work involving IP and ground 

magnetic surveys over the main copper in soil anomalies may help to delineate any sulphiderich 

zones for further work. 

Several other prospects and geochemical anomalies (e.g. Mamuring 1 and Rinjen) within the 

KSK COW have received limited exploration attention. These require collection of basic 

geological data, geochemical data and mineralized samples in order to allow their potential to 

be assessed. The potential for high-grade skarn-style copper-gold mineralization at Mamuring 

should be investigated. 

Although the recent work resulted in downgrading of some prospects, further work within the 

KSK COW is warranted to assess the potential of several untested porphyry copper targets. 

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Copper potential of KSK COW, Central Kalimantan

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Table of Contents 

Executive Summary.......................................................................................................2 

Table of Contents...........................................................................................................3 

Statement of experience.................................................................................................4 

Introduction....................................................................................................................5 

Approach........................................................................................................................5 

Geological setting ..........................................................................................................5 

Porphyry copper prospects.............................................................................................8 

Beruang Kanan...............................................................................................................9 

Oxiana Limited drilling............................................................................................13 

Discussion................................................................................................................14 

Baroi.............................................................................................................................16 

Oxiana Limited Drilling...........................................................................................16 

Discussion................................................................................................................17 

Mansur .........................................................................................................................18 


Discussion................................................................................................................19 

Beruang Tengah...........................................................................................................20 


Discussion................................................................................................................21 

Tumbang Huoi .............................................................................................................22 

Conclusions..................................................................................................................23 

References (including uncited reports) ........................................................................24 

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Statement of experience 

Dr Peter Pollard is a consulting economic geologist with more than 20 years 

experience. He holds a PhD from James Cook University, Australia and is a Member 

of the Australasian Institute of Mining and Metallurgy and a Fellow of the Society of 

Economic Geologists. 

Dr Pollard has consulted widely on porphyry copper-gold and iron oxide copper-gold 

deposits. He has worked on some of the world’s major porphyry copper-gold deposits 

including Grasberg (Indonesia), Escondida Norte (Chile) and Oyu Tolgoi (Mongolia). 

In addition, he has consulted on porphyry exploration programs in Australia, China, 

Indonesia, Iran, Kazakhstan, Mongolia, Peru, U.S.A. and Vietnam. 

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Introduction 

At the request of Mr Rahman Connelly of Kalimantan Gold Corporation Limited, the 

author spent 4 days in Palangkaraya, Kalimantan reviewing the results of recent 

exploration within the P.T. Kalimantan Surya Kencana Contract of Work (KSK 

COW; Figs 1 and 2). The aim of this work was to evaluate the copper potential of the 

COW following the 2007 exploration program conducted by Oxiana Limited in joint 

venture with Kalimantan Gold Corporation Limited. 

Approach 

Oxiana Limited undertook an exploration program within the KSK COW in 2007 

with a target of +300 million tonnes at 1% Cu. The exploration program involved 

geological mapping, re-logging of drill core and reprocessing of geophysical and 

geochemical data as well as drilling 16 new diamond drill holes in the Beruang 

Kanan, Beruang Tengah, Baroi and Mansur prospects. The drill holes mostly returned 

low grades of copper and gold and Oxiana subsequently withdrew from the joint 

venture. The current review considered the Oxiana Limited data as well as previous 

exploration data on these four prospects in order to assess their copper potential. In 

addition, the copper potential of the Tumbang Huoi prospect is also briefly 

considered. 

Geological setting 

The KSK COW is situated within the mid-Tertiary Kalimantan volcanic arc that hosts 

a number of porphyry copper-gold deposits and prospects including Mamut, Rina, 

Manto-Tebihi and those within the KSK COW. In addition, several low sulphidation 

epithermal deposits are present including Kelian, Indo Muro, Masuparia, Gunung Mas 

and Jelai-Mewet. 

Porphyry copper-gold mineralization in the KSK COW is associated with a number of 

probable Oligocene age intrusions that were emplaced at the junction between 

Mesozoic metamorphic rocks to the south and accreted Lower Tertiary sediments to 

the north (Geiger and Prasetyo, 2004). Structures in the region are dominated by 

northeast-striking faults that are interpreted to be arc parallel or accretionary faults 

(Geiger and Prasetyo, 2004). Subsidiary northwest-trending arc normal or transfer 

faults cross-cut the northeast structures and the intrusions have commonly been 

emplaced within dilational settings at the intersections of these major structural 

features (Geiger and Prasetyo, 2004). 

Large circular features that are evident on satellite images commonly coincide with 

the mid-Tertiary intrusions and are interpreted to be volcanic collapse features (Geiger 

and Prasetyo, 2004). These host many of the porphyry prospects within the KSK 

COW. 

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Figure 1. Location of the Kalimantan Surya Kencana Contract of Work within the 

Kalimantan magmatic arc. 

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Figure 2. Principal prospects and geochemical anomalies within the Kalimantan 

Surya Kencana Contract of Work. 

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Porphyry copper prospects 

Previous exploration in the KSK COW has used a model of porphyry copper systems 

in the SW Pacific (Corbett and Leach, 1998; Geiger et al., 2002) as a general guide. 

The main porphyry prospects within the KSK COW have been placed within this 

general framework by Geiger et al. (2002) based on the observed alteration features 

and proximity of porphyry intrusions (Fig. 3). This model does not attempt to identify 

the size of porphyry systems in terms of surface or other dimensions and it is not clear 

whether an ‘economic porphyry system” in the KSK COW would be a broad 

intrusion-centered body of mineralization at kilometre scale or a narrow, structurally 

controlled zone of high-grade mineralization at 100-400m scale in plan. Concepts 

concerning room available to host a deposit need to be considered in this light as 

recent exploration successes at Ridgeway (Australia) and Oyu Tolgoi (Mongolia) 

have highlighted the occurrence of porphyry systems with limited surface expression 

linked to narrow dyke- or pencil-like intrusions. 

Figure 3. General model of Southwest Pacific porphyry copper systems (modified 

from Geiger et al., 2002). 

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Beruang Kanan 

The Beruang Kanan prospect is located within a 10-12 km wide circular feature near 

the intersection of regional NE and NNW-trending structures (Fig. 4). Alteration and 

mineralization at Beruang Kanan extends over an area of some 16 km 2 and is hosted 

within dacite tuff and volcaniclastic rocks. Soil geochemistry and geophysical data (IP 

and ground magnetics) have delineated three main prospects, the Main, South and 

West zones. 

Figure 4. Interpreted circular features, domes, faults and dilation zones in the 

southeastern part of the KSK COW (after Murphy, 2003). 

The Main Zone is an area of coincident copper, gold and molybdenum anomalism in 

soils and is associated with strong phyllic alteration (Figs. 5-7). Leach (2001) reported 

that alteration is zoned from deeper to shallower levels: chlorite-sericite-quartz-pyritechalcopyrite 

→ quartz-sericite-pyrite-chalcopyrite-bornite → quartz-dickite/kaolinitepyrite-chalcopyrite-bornite-tennantite 

→ quartz-alunite-pyrite-barite-enargite. Leach 

(2001) also reported an apparent zonation from chlorite-sericite-rich assemblages at 

deeper levels to the east to advanced argillic assemblages at shallow levels to the 

west, suggesting a fluid source deeper and to the east. 

Previous drilling in the Main Zone has intercepted potentially economic grades of 

copper mineralization over considerable down hole intervals (Table 4). Near surface 

mineralization is dominated by supergene chalcocite and minor chrysocholla and 

malachite, while at deeper levels the hypogene mineralization is dominated by 

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chalcopyrite ± bornite. Leach (2001) constructed cross sections highlighting the 

alteration, grade distribution and IP chargeability features along line 10050N (Figs. 6- 

8) and considered two sources for the mineralization: 

1. copper mineralization related to a breccia pipe inferred from milled breccia 

observed in BK8 (Fig. 5), or 

2. copper mineralization derived from another source, perhaps represented by a 

high chargeability anomaly. 

Table 1. Copper grades in earlier drill holes from the Beruang Kanan prospect (from 

Geiger et al., 2005). 

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Figure 5. Interpretive cross section with drill holes projected on to line 10050N 

showing the distribution of alteration and sulphide mineral types (from Leach, 2001). 


showing the distribution of copper grades (from Leach, 2001). 

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showing the distribution of chargeability anomalies (from Leach, 2001). 

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Oxiana Limited drilling 

Oxiana drilled 10 holes at Beruang Kanan (Fig. 8) where reprocessing of the IP data 

led them to believe that there was a strong correlation between near-surface 

conductive and chargeable zones and copper in drill holes and soils (Stewart et al., 

2007). 

Drill hole Location Azimuth Inclination Length (m) 

KBK0019 South Zone 090 o -60 o 303.65 

KBK0200 Main Zone 090 o -70 o 304.90 




KBK0024 South Polymetallic 090 o -70 o 305.00 

KBK0025 South Polymetallic 090 o -90 o 393.20 


KBK0027 West Zone 070 o -60 o 278.70 

KBK0028 South Zone 090 o -70 o 151.30 

Table 2. Oxiana Limited drill holes at the Beruang Kanan Prospect (data from 

Stewart et al., 2007). 

Drill hole From (m) To (m) Cu (%) Au (g/t) 

KBK0020 9.6 52.0 0.12 

KBK0021 16.6 60.6 0.58 

KBK0021 147 188.7 0.46 

KBK0024 95.5 136.0 0.51 

KBK0028 0.0 61.0 0.21 

KBK0028 10.0 14.5 7.7 

Table 3. Significant intercepts in Oxiana drill holes at the Beruang Kanan Prospect 

(data from Stewart et al., 2007).. 

Five holes were drilled in the Main Zone and most targeted chargeability anomalies 

suspected to represent either shallow supergene mineralization or deeper, hypogene 

mineralization (e.g. KBK0021). In addition, one hole (KBK0020) tested the 

possibility that a buried porphyry could be represented by a low chargeability zone 

((Stewart et al., 2007). 

In the South Zone, two holes were sited in an area of high density quartz-sulphide 

stockwork veining with anomalous gold, molybdenum and copper soil geochemistry. 

Hole KBK0028 intersected 61m @ 0.21% Cu from surface, including 4.5m @ 7.7g/t 

Au from 10m. In the South Polymetallic Zone (Rawa Zone), two holes tested the base 

metals zone with limited success. One hole was drilled in the West Zone where an 

extensive area of anomalous copper in soil geochemistry is present. The drill hole did 

not intersect any significant mineralization and the last 100 metres was in postmineral 

porphyry. 

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Figure 8. Geology of the Beruang Kanan prospect showing the distribution of drill 

holes (modified from Stewart et al., 2007). 

Discussion 

Of the two holes in the Main Zone which returned significant intersections (Table 3), 

one was drilled in a high chargeability zone (KBK0021) and the other in a low 

chargeability zone (KBK0020). This must raise a question over the inferred 

relationship between chargeability and copper mineralization in this area and suggests 

that interpretations based solely on the IP data must be treated with caution. 

The principal porphyry target in the Main Zone delineated by Leach (2001) was not 

tested by the recent drilling and the mineralization still remains open at depth in the 

area near BK09. In order to test this target, holes would need to be sited east and 

northeast of BK09 and drilled to the west at -50-60 o . 

In the South Zone, KBK0028 appears to have been drilled some 200 metres south of 

the main soil geochemistry and IP target described by Geiger et al. (2005)(see fig. 9). 

The main target zone therefore remains untested. 

Strong clay-pyrite alteration is present in the west zone but the source of copper and 

the style of any copper mineralization are not known. Further work could be 

undertaken to identify the style(s) of mineralization. This could involve mapping 

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within the copper anomalous areas as well as outcrop and boulder sampling. If 

positive indications for the presence of porphyry style mineralization are found, then 

it may be considered worthwhile drilling the western part of the deep chargeability 

anomaly beneath the resistive siliceous porphyry dome(?) as interpreted on line 

9965N at around 13000E (see Geiger et al., 2005). 

Figure 9. Soil geochemistry, IP anomaly and stockwork vein distribution at Beruang 

Kanan South Zone (Geiger et al., 2005) showing the location of two holes drilled by 

Oxiana Limited. 

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Baroi 

The Baroi prospect is located within the southwestern part of the KSK COW (Fig. 1) 

and is hosted within an 8 km wide circular feature which is interpreted as a caldera 

structure. The main lithologies at Baroi include andesitic volcanics which have been 

intruded by monzonite and dacite porphyry intrusions at the margin of a large 

granodiorite pluton. The alteration and mineralization explored to date occurs in the 

southern part of the circular structure where it is intersected by regional NE and NNW 

oriented structures. The Central Zone and the Far East Zone have been the focus of 

exploration to date. 

Mineralization in both the Central and Far East Zones is hosted by northwest and 

north northwest-trending veins up to 10 metres wide. The veins typically contain 

chalcopyrite, galena and sphalerite together with quartz and chlorite. Hole BF05 

drilled 83 metres down the dip of one such vein and returned 2.64% Cu, 0.62% Pb, 

1.85% Zn and 61 g/t Ag and 0.22 g/t Au. SRK considered that the vein density is not 

high enough to form a significant resource (Munroe and Clayton, 2006) however, they 

may ultimately offer small volumes of high grade material to supplement other ore 

sources. Deep drilling at the Far East Zone (to 600 metres) has not indicated the 

presence of shallow porphyry style mineralization beneath the vein system. 

Veins similar to those at Far East also occur in the Central Zone where a number of 

short holes have intersected a series of subparallel veins with Zn ≥ Pb ≥ Cu. The 

predominance of sericitic and argillic alteration coupled with the presence of these 

base metal veins in the Central Zone is consistent with the exposed material 

representing the outer/upper parts of a porphyry system. 

Oxiana Limited Drilling 

Oxiana drilled two new holes at Baroi, one in a conceptual target in Central Baroi 

originally defined by Burke (1996) on the basis of coincident magnetic and resistivity 

anomalies flanked by conductivity highs, and the other in the Far East Zone in an area 

of weakly anomalous copper and gold geochemistry. 

KBC009 in Central Baroi was drilled to a depth of 542.6m without intersecting 

significant mineralization. The presence of unaltered carbonaceous shale underlying 

andesitic volcanics was believed to explain the resistivity contrast. 

KBF0050 in Far East Baroi intersected several quartz-chalcopyrite-pyrite-chlorite 

veins which were thought to be up to 0.5m wide. Significant intercepts comprise 

(Stewart et al., 2007): 

• 14 metres @ 1.61 ppm Ag and 1710.57 ppm Cu (from 30 metres); 

• 30 metres @ 0.12 ppm Au, 7.11 ppm Ag and 6586 ppm Cu (from 56 metres); 

• 6 metres @ 0.11 ppm Au, 6.73 ppm Ag and 5223.33 ppm Cu (from 112.00 

metres). 

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Discussion 

The conceptual target in Central Baroi proposed by Bob Burke on the basis of 

geophysical data was tested by KBC009. Reprocessed IP data led Rowston (2007) to 

downgrade the significance of this target because of the low chargeability in the 

central part. Even though the hole appears to have stopped short of the central part of 

the target, it does appear to have intersected the marginal chargeability anomaly 

flanking the central zone which was envisaged as a potential pyrite-rich shell. No 

significant mineralization was present in the hole and the amount of pyrite was 

generally low. The drill hole did intersect several zones of milled breccia containing 

pyrite and silica-pyrite fragments, but the lower part of the hole was composed of 

carbonaceous shale. The lack of strong pyrite development and the presence of 

carbonaceous shale suggest that the target should be downgraded. 

Two further targets in central Baroi proposed by Pollard (2006) were not drilled 

despite receiving support from the reprocessed IP data (Rowston, 2007). The large 

high chargeability feature observed on the old level 7 chargeability data on the 

western side of Baroi Central could represent a zone of sulphide mineralization above 

a buried porphyry intrusion (Geiger and Prasetyo, 2004). Although this was partially 

tested in BC-08, a further hole was suggested via drilling the proposed hole BC-09 on 

line 30600N (Geiger and Prasetyo, 2004; Pollard, 1996). Based on the reprocessed IP 

data, Rowston (1977) supported drilling a 400m vertical hole in this conductive, 

chargeable feature at 30600N and 45800E. 

The resistivity low and chargeability high located near 30800N and 48200E, was also 

proposed as a target worth drilling by Pollard (2006). This area is a gap in the mapped 

NW-trending base metal vein system and is associated with a topographic low. It is 

potentially the centre and source region of the vein system and it was recommended 

(Pollard, 2006) that all drill hole data from the eastern sector (Baroi Far East) be 

examined for temperature vectors (trends in ratios of Zn/Pb, Cu/Zn, etc.) toward this 

area. If present, they would support drilling a deep hole to test for mineralization 

linked to a deeper porphyry, possibly associated with sericitic alteration similar to that 

reported from holes BB-01 and BB-02. Rowston (2007) also advanced this area as a 

target based on the reprocessed IP data. 

KBF0050 confirmed previous interpretations that shallow porphyry style 

mineralization is not present beneath the vein system at Far East Baroi. 

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Mansur 

The Mansur prospect is located in the northwestern portion of the KSK COW within a 

circular topographic feature and associated strong magnetic anomaly. Surface 

mapping indicates the presence of a diorite intrusion within a sequence of sediments 

that includes siltstone, sandstone and chert. Potassic alteration in the form of biotite ± 

magnetite alteration and/or K-feldspar veins and alteration forms a broad zone 

extending more than 500 metres east and west of the diorite within the sedimentary 

sequence. A semicircular zone of >500 ppm Cu in soils extends around the western 

side of the diorite (Fig. 10) within the zone of potassic alteration. 

Previous drilling at Mansur had focused on the gold in soil anomaly which occurs 

mainly within the diorite and this returned mostly low grade values for copper and 

gold (e.g. CSM1 – 250m @ 873ppm Cu and CSM3 – 250m @ 1180ppm Cu and 0.06 

g/t Au; KSK Staff, 2006). Trenching over the Cu in soil anomaly produced low 

copper and gold values (70-1210 ppm Cu and

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Figure 10. Soil geochemistry and drill hole location at the Mansur Prospect (from 

Johansen, 2997). 

Discussion 

The new drilling at Mansur appears to have downgraded the prospect and the chance 

of discovering an economic porphyry system in the area defined by the soil copper 

anomaly is now considered to be low. The new holes together with the earlier Cyprus 

Amax holes (CSM1 – 250m @ 873 ppm Cu and CSM3 – 250m @ 1180 ppm Cu and 

0.06 g/t Au) have effectively tested this area without intersecting significant widths or 

grades of mineralization. 

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Beruang Tengah 

The Beruang Tengah prospect is hosted within the same circular structure and 

southeast of Beruang Kanan (Fig. 4). Copper-gold mineralization is hosted within 

dioritic to dacitic intrusions that were emplaced between sediments and tuffs to the 

west and older granodiorite to the east. A zone of intense quartz-sericite alteration and 

sheeted sulphide-quartz veins surrounds a central zone of biotite-magnetite alteration, 

and quartz stockwork veins crop out at lower levels (Geiger and Prasetyo, 2004). A 

400 metre wide zone of >0.1% copper in rock chips (Fig. 11) coincides with the zone 

of quartz-sericite alteration. Some 500 metres to the west, a 1 km long zone of phyllic 

alteration coincides with a zone of >0.1 g/t Au in soils (Geiger and Prasetyo, 2004). 

Three previous diamond drill holes intersected low-grade copper-gold mineralization 

at Beruang Tengah (e.g. BT2 – 240 metres @ 0.19% Cu and 0.12 g/t Au) and together 

with the mapped alteration at surface, have indicated the presence of a porphyry 

copper-gold system with significant molybdenum. 

Oxiana Limited drilling 

Oxiana Limited drilled one additional hole at Beruang Tengah which targeted high 

copper in rock chips (Fig. 11), known phyllic alteration, as well as an outcropping 

milled breccia. The hole returned low values of copper and gold (Table 4), especially 

in the milled breccia which from observations of the skeleton core is a post-mineral 

feature. 

Drill hole From (m) To (m) Cu (%) Au (g/t) Mo (ppm) 

KBT 004 19.7 121.0 0.12 0.2 42 

KBT 004 232.2 507.5 0.08 185 

Table 4. Mineralized intercepts in KBT004 at Beruang Tengah. 

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Figure 11. Rock chip copper geochemistry and location of drill holes at Beruang 

Tengah (from Johansen, 2007). 

Discussion 

The new drilling at Beruang Tengah has significantly downgraded this part of the 

system and Oxiana considered that there was insufficient room remaining within the 

prospect for an economic porphyry deposit. 

The Beruang Tengah prospect area has been defined from rock chip sampling of creek 

outcrops rather than by a broader soil sampling program. It is considered that followup 

work is warranted aimed at more fully delineating the extent of veining and 

mineralization and identifying sulphide-rich parts of the system. Stockwork and 

sheeted veins with limonites after sulphides extend to the south and west beyond the 

copper anomaly that has been the focus of recent work (Geiger, pers. comm., 2008). 

Extension of the geochemical coverage into these areas via a soil survey together with 

an IP survey over the main copper anomalies may serve to highlight sulphide-rich 

parts of the system for follow-up drilling. Given the observed association of 

secondary biotite and magnetite in several of the KSK prospects, reprocessing of the 

existing ground magnetic data and extension to the new soil grid may also serve to 

better highlight structure and alteration distribution. 

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Tumbang Huoi 

The Tumbang Huoi prospect is located within a large circular structure in the 

southwest part of the KSK COW (Fig. 2). Mapping and sampling were undertaken in 

the latter part of 1987 and 15 short holes were drilled in 1992 primarily focused on 

gold. Potassic alteration characterized by veins and wispy trails of biotite ± magnetite 

and veins with K-feldspar ± quartz is present in several drill holes and copper in soil 

anomalies are present in several parts of the prospect (Fig. . Further work perhaps 

involving extension of the soil grid, together with IP and ground magnetic surveys is 

needed in order to highlight possible sulphide-rich parts of the prospect. 

Figure 12. Copper in soil map of the Tumbang Huoi prospect. 

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Conclusions 

This brief review of recent exploration of the major porphyry copper prospects within 

the KSK COW in Central Kalimantan indicates that several of these systems still have 

untested potential. In particular, the Beruang Kanan Main and South Zones and the 

Baroi Central prospect have untested drill targets that were proposed in earlier work 

by KSK staff and external consultants. The Baroi targets were also supported 

following reprocessing of the IP data during the Oxiana joint venture. 

Several other prospects within the KSK COW including Beruang Tengah, Tumbang 

Huoi, and Beruang West require further field inspection, geochemical sampling and 

geophysical work in order to define targets for further exploration. Other prospects 

not considered here including Rinjen and Mamuring also require further work, 

especially to assess the potential for high-grade skarn-style mineralization at 

Mamuring. 

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Acknowledgements 

The author would like to acknowledge the help provided by KSK staff in 

Palangkaraya, especially Mansur Geiger, Didik Prasetyo and Rachmat Setiawan 

References (including uncited reports) 

Corbett, G.J. and Leach, T.M., 1998. Southwest Pacific rim gold-copper systems: 

structure, alteration and mineralization. Society of Economic Geologists Special 

Publication No. 6, 236p. 

Geiger, M. and Prasetyo, D., 2004. Appraisal and exploration summary: Baroi and 

other significant prospects, KSK Contract of Work, Central Kalimantan, Kalimantan, 

Indonesia. Unpublished report to P.T. Kalimantan Surya Kencana. 

Geiger, M., Prasetyo, D. and Setiawan, R., 2002. Sungai Mansur data review. 

Unpublished report to P.T. Kalimantan Surya Kencana. 

Geiger, M., Prasetyo, D. and Setiawan, R., 2005. Beruang prospects exploration 

summary. Unpublished report to P.T. Kalimantan Surya Kencana. 

Geiger, M., Prasetyo, D. and Leach, T., 2002. Porphyry copper-gold systems in 

Central Kalimantan. Prospectors and Developers Association of Canada Annual 

Convention, 2002, 16p. 

Johansen, G., 2007. Report on the geology and copper potential of the KSK JV 

tenements in Central Kalimantan. Oxiana Limited report No. 1140. 

KSK Staff, 2004. Beruang drilling report: Drill hole summary and sections including 

Beruang Kanan, Beruang Tengah, Hulu Beruang Kanan Gold Zone, Beruang Kanan 

Polymetallic North. Unpublished report P.T. Kalimantan Surya Kencana. 

KSK Staff, 2006. Sungai Mansur exploration program 2006. Unpublished report to 

P.T. Kalimantan Surya Kencana. 

Leach, T., 2001. Comments on exploration activity at the Beruang Kanan porphyry 

copper prospect, Central Kalimantan. Unpublished report to P.T. Kalimantan Surya 

Kencana. 

Murphy Geological Services, 2003. Interpretation of aerial photographs, Landsat 

ETM+ and Radarsat imagery for an area in Central Kalimantan. Unpublished report to 

P.T. Kalimantan Surya Kencana. 

Olii, U., 1999. Report on Tumbang Huoi prospect, Upper Kahayan River, Central 

Kalimantan, Indonesia. Unpublished report to P.T. Kalimantan Surya Kencana. 

Omer-Cooper, W., 1990. P.T. Pancaran Paringa Kalimantan Riah Janda Contract of 

Work: Tumbang Huoi gossan, Unpublished report 4p and appendices. 

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Pollard, P.J., 2006. Copper(-gold) prospects within the Kalimantan Surya Kencana 

Contract of Work, Kalimantan, Indonesia: Review and recommendations for future 

exploration. Unpublished report to Kalimantan Gold Corporation Limited. 

Prasetyo, D., 1999a. Drilling data: Beruang Tengah porphyry copper-gold. 


Prasetyo, D., 1999b. Drilling data: Mamuring porphyry-related copper-gold veins. 


Prasetyo, D. and Setiawan, R, 2001. Drill holes summary BK-11 to BK-18 Beruang 

Kanan Prospect. Unpublished report to P.T. Kalimantan Surya Kencana. 

Richardson, J., 1996. PT Cyprus Amax Indonesia: Mansur Project Central 

Kalimantan, Exploration Summary March 15 – September 15, 1996, vol. 1. 

Unpublished report. 

Rowston, P., 2007. Copper-gold porphyry prospect geophysics Baroi Central/East, 

Central Kalimantan: Modeling and interpretation report. Unpublished report by 

Geophysical Resources and Services Pty. Ltd. 

SRK Consulting, 2006. Competent person’s report on the mineral exploration assets 

of Kalimantan Gold Corporation Limited. Unpublished report to Kalimantan Gold 

Corporation. 

Stewart, A., Smith, S., Hamid, D. and Muryanto, A., 2007. 2007 exploration report 

KGC COW project, Central Kalimantan, Republic of Indonesia. Oxiana Limited 

report No. 1141. 

Wake, B. and Setiawan, R., 2006. Baroi Prospect, Baroi Far East Zone deep diamond 

drilling report (interim). Unpublished report to P.T. Kalimantan Surya Kencana. 

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Copper potential of KSK COW - Kalimantan Gold Corporation Limited

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